Adding upstream version 2.1.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

examples/custom_stylesheets/inlineOutput.svg

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+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="512" height="512">\n<style type="text/css"><![CDATA[svg .background { fill: white; }svg .canvas { fill: white; }svg path.blue { fill: blue; stroke: lightblue; }svg path.green { fill: green; stroke: lightgreen; }svg path.gray { fill: gray; stroke: lightgray; }svg text.blue { fill: white; }svg text.green { fill: white; }svg text.gray { fill: white; }]]></style><path  d="M 0 0
+L 512 0
+L 512 512
+L 0 512
+L 0 0" class="background"/><path  d="M 5 5
+L 507 5
+L 507 507
+L 5 507
+L 5 5" class="canvas"/><path  d="M 256 256
+L 507 256
+A 251 251 128.56 0 1 100 452
+L 256 256
+Z" class="blue"/><path  d="M 256 256
+L 100 452
+A 251 251 128.56 0 1 201 12
+L 256 256
+Z" class="green"/><path  d="M 256 256
+L 201 12
+A 251 251 102.85 0 1 506 256
+L 256 256
+Z" class="gray"/><text x="313" y="413" class="blue">Blue</text><text x="73" y="226" class="green">Green</text><text x="344" y="133" class="gray">Gray</text></svg>

examples/custom_stylesheets/main.go

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+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/wcharczuk/go-chart/v2"
+)
+
+const style = "svg .background { fill: white; }" +
+	"svg .canvas { fill: white; }" +
+	"svg .blue.fill.stroke { fill: blue; stroke: lightblue; }" +
+	"svg .green.fill.stroke { fill: green; stroke: lightgreen; }" +
+	"svg .gray.fill.stroke { fill: gray; stroke: lightgray; }" +
+	"svg .blue.text { fill: white; }" +
+	"svg .green.text { fill: white; }" +
+	"svg .gray.text { fill: white; }"
+
+func svgWithCustomInlineCSS(res http.ResponseWriter, _ *http.Request) {
+	res.Header().Set("Content-Type", chart.ContentTypeSVG)
+
+	// Render the CSS with custom css
+	err := pieChart().Render(chart.SVGWithCSS(style, ""), res)
+	if err != nil {
+		fmt.Printf("Error rendering pie chart: %v\n", err)
+	}
+}
+
+func svgWithCustomInlineCSSNonce(res http.ResponseWriter, _ *http.Request) {
+	// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/style-src
+	// This should be randomly generated on every request!
+	const nonce = "RAND0MBASE64"
+
+	res.Header().Set("Content-Security-Policy", fmt.Sprintf("style-src 'nonce-%s'", nonce))
+	res.Header().Set("Content-Type", chart.ContentTypeSVG)
+
+	// Render the CSS with custom css and a nonce.
+	// Try changing the nonce to a different string - your browser should block the CSS.
+	err := pieChart().Render(chart.SVGWithCSS(style, nonce), res)
+	if err != nil {
+		fmt.Printf("Error rendering pie chart: %v\n", err)
+	}
+}
+
+func svgWithCustomExternalCSS(res http.ResponseWriter, _ *http.Request) {
+	// Add external CSS
+	res.Write([]byte(
+		`<?xml version="1.0" standalone="no"?>` +
+			`<?xml-stylesheet href="/main.css" type="text/css"?>` +
+			`<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">`))
+
+	res.Header().Set("Content-Type", chart.ContentTypeSVG)
+	err := pieChart().Render(chart.SVG, res)
+	if err != nil {
+		fmt.Printf("Error rendering pie chart: %v\n", err)
+	}
+}
+
+func pieChart() chart.PieChart {
+	return chart.PieChart{
+		// Note that setting ClassName will cause all other inline styles to be dropped!
+		Background: chart.Style{ClassName: "background"},
+		Canvas: chart.Style{
+			ClassName: "canvas",
+		},
+		Width:  512,
+		Height: 512,
+		Values: []chart.Value{
+			{Value: 5, Label: "Blue", Style: chart.Style{ClassName: "blue"}},
+			{Value: 5, Label: "Green", Style: chart.Style{ClassName: "green"}},
+			{Value: 4, Label: "Gray", Style: chart.Style{ClassName: "gray"}},
+		},
+	}
+}
+
+func css(res http.ResponseWriter, req *http.Request) {
+	res.Header().Set("Content-Type", "text/css")
+	res.Write([]byte(style))
+}
+
+func main() {
+	http.HandleFunc("/", svgWithCustomInlineCSS)
+	http.HandleFunc("/nonce", svgWithCustomInlineCSSNonce)
+	http.HandleFunc("/external", svgWithCustomExternalCSS)
+	http.HandleFunc("/main.css", css)
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}